1. Field of the Invention
This invention relates to a process for making 1-alkyl-5-mercaptotetrazoles.
2. Description of the Prior Art
1-Alkyl-5-mercaptotetrazoles (also called 1-alkyltetrazole-5-thiols) are useful intermediates for making cephalosporin-type antibiotics. This class of chemical intermediates has been made by various routes. For example, these compounds have been prepared by the addition of metal azides to isothiocyanates; by the displacement of the alkylmercapto group from alkyl (N-alkyl) dithiocarbamate with metal azides; by the displacement of a halogen atom from a 5-halotetrazole with a sulfur nucleophile; and by reaction of a sulfur-protected thiosemicarbazide with nitrous acid followed by removing the protecting group from the sulfur.
While these reported syntheses have academic interest, they all suffer commercial disadvantages of either employing multi-pot reactions or starting from expensive or possibly hazardous reactants (e.g., metal azides) or have all of these problems. Thus, there is a need in the art for a simple one-pot synthesis starting from relatively inexpensive reactants. The present invention is believed to be a solution to that need.